简介：Manyofthehighstrength,hightoughnesssteelsinuseorunderdevelopmentarealloysteelswithdislocatedlathmartensiticstructures.Thesemicrostructuresarevisuallycomplex,andaredifficulttocategorizeinthedetailneededtoclarifythestructure-propertyrelations.However,substantialprogresshasbeenmadeinrecentyears.Inparticular,itisnowclearthatthemartensiteblockelementsetstheeffectivegrainsizethatmustbecontrolledtoresistbrittlenessbycleavagefracture.InpreviouspapersatthisconferenceIhavediscussedthenatureandimportanceoftheblockstructure.InthisstudyIdiscusshowtheblocksizecanbecontrolledbythermaltreatmentstoachievesuperiorproperties.

简介：Strainageinginsteelwasfirstobservedduringthe19thcenturywhenthemaximumloadcarryingcapacityofatestpiecewasincreasedafterithadbeenretestedfollowingapreviousseriesoftestinginaplasticrange.Overthelastdecades,agreatdealofresearchhasbeenperformedtogaindeeperinsightsintothephenomenonofstrainageing.Thesynergisticdevelopmentoftheoreticalhypothesisandnewexperimentalevidenceshaspromotedtheunderstandingofthemechanismsunderlyingstrainageing.Thecontentofthispaperisorganizedintofourcomponents.First,wehavecomparedthemaintheoriesdevelopedinrecentyears.Second,wehavesummarizedthemetallurgicaleffectsonthestrainageingbehaviorobservedinexperiments.Moreover,wehavemadeanattempttocorrelatetheexperimentalresultsandtheabove-mentionedtheories.Third,wehaveproposedafeasiblesolutiontocontrolstrainageinginlowcarbonsteels.Finally,wehaveelaboratedthepotentialityoftheatomprobetechniqueinfacilitatingdirectcharacterizationofthedistributionofsoluteatoms.

简介：Thisstudyinvestigatesthemicrostructuresofmicroalloyedsteelsbeforeandafterstrainageingtreatment.Itwasfoundthatthemicrostructureconsistedofbothlathferriteandpearlite.Mostofthecarbidesand/ornitridesofmicroalloyingelementsweredistributedinsidethegrainswithasmallamountdistributedatthegrainboundaries.Theprecipitatedphasesinsidethegrainsweremuchsmallerinsizethanthoseatthegrainboundaries.Theprecipitatesareeithercircularorshortbar-like,ofsizesfromafewnanometerstoseveralhundrednanometers.Afterageing,onlycarbonatomssegregatearoundthedislocationsandnitrogendoesnotparticipateinproducingtheCottrellatmospherebecauseitwasfixedbyalloyingelementsbeforeageing.

简介：Inthisstudy,resistancespotweldabilityof180gradebakehardeningsteel(BH180),7123gradeinterstitialfreesteel(IF7123)and304gradeausteniticstainlesssteel(AISI304L)witheachotherwasinvestigated.Inthejoiningprocess,electrodepressureandweldcurrentwerekeptconstantandsixdifferentweldtimewerechosen.Microstructure,microhardness,tensile-shearpropertiesandfracturetypesofresistancespotweldedjointswereexamined.Inordertocharacterizethemetallurgicalstructureoftheweldedjoint,themicrostructuralprofilewasdeveloped,andtherelationshipbetweenmechanicalpropertiesandmicrostructurewasdetermined.Thechangeofweldtime,nuggetdiameter,theHAZ(heataffectedzone)widthandtheelectrodeimmersiondepthwerealsoinvestigated.WeldedjointswereexaminedbySEM(scanningelectronmicroscopy)imagesoffracturesurface.Asaresultoftheexperiment,itwasdeterminedthatwithincreasingweldtime,tensileshearloadbearingcapacity(TLBC)increasedwithweldtimeupto25cycleandtwotypesoftearingoccurred.ItwasalsodeterminedthatwhilethefailureoccurredfromIFsideattheBH180+IF7123joint,itoccurredfromtheBH180sideattheBH180+AISI304Ljoint.

简介：Ultra-steelProjectperformedatNationalInstituteforMaterialsScience(NIMS)1997-2005proposed'Breakthroughsforinnovationbysteelscience'.Themainconceptswerecomposedofdecreasingtheenvironmentalload,noorlessspecialalloyingelementsandsaferinfrastructurewithreducedthetotallifecost.Four'doublestrengthanddoublelife'steelsweredevelopedasfollows:①800MPa-classecologicallybeneficialsteelsforweldedstructures,②1500MPasteelswithhighresistancetofracture,③advancedferriticsteelsfor650C-USCboilersand④Ultra-steelsforstructuresinmarineandoffshoreenvironments.Worldsteelsocietyisstillgrowingwiththreateninglimitsofresourcesandenergy.Applicationoftheultra-steelideaswouldbeincreasinglyhelpfulfortheglobalsustainability.ThetalkwillintroducetherecentprogressinsteelresearchatNIMS,basedontheprojectaccomplishments.

简介：Withtheextensivelywideapplicationofadvancedhighstrengthsteels(AHSS)invariousfieldsfortheexcellentmechanicalproperties,theindustrialinterestonthedamageofAHSSisincreasingintherecentyears.Forthesemodernsteels,duetothecomplexmicrostructureandtherelevantdeformationmechanisms,thedamageconceptneedstobereexamined.Inthispaper,thedefinition,lengthscaleanddifferentmechanismsofdamageareintroduced.Bothexperimentalevaluationofdamageandthenumericaldamagemodelsarebrieflyviewedandcompared.Theapproachestoimprovethedamagetolerancearegivenintheframeworkofdamagetolerancedesignprinciple.

简介：Acicularferritemicrostructurewasachievedforanultralowcarbonpipelinesteelthroughtheimprovedthermomechanicalcontrolprocess(TMCP),whichwasbasedonthetransformationprocessofdeformedausteniteofsteel.Comparedwithcommercialpipelinesteels,theexperimentalultralowcarbonpipelinesteelpossessedthesatisfiedstrengthandtoughnessbehaviorsunderthecurrentimprovedTMCP,althoughitcontainedonlyapproximately0.025%C,whichshouldmainlybeattributedtothemicrostructuralcharacteristicsofacicularferrite.

简介：Pre-paintedsteelisoneofthemostimportantstructuralmaterialofthe20thcenturywellknownforitsexcellentcorrosionresistanceandwiderangingapplications.Atypicalpre-paintedsteelusuallyconsistsofalayerofmetalcoatingsystem,preferablyzincorzincalloycoatingandacombinationoflayersofinorganic-organiccoatingsusuallyreferredtoaspaintsystem.Thecorrosionresistanceofthemetalcoatingaswellasthepaintsystemmayvaryconsiderablybasedontheircompositionandtheenvironment.Foroptimalcorrosionperformanceofpre-paintedsteel,ajudiciousselectionofbothmetalandinorganic-organiccoatingsystemsareessential.Thispaperreviewsdifferenttypesofpossiblecorrosionissuesinpre-paintedsteelsandmethodstooptimisetheirperformance.

简介：为生产导致的冷卷的转变的热处理过程帮助粘性(帮助旅行)有bainitic铁酸盐矩阵的钢被采用。在如此的旅行钢的保留的奥氏体(RA)的特征被调查。SEM和OM决心结果证明在房间温度保留的稳定的奥氏体主要在粗糙的铁酸盐内在他们的板条和一些之间被定位。谷物一致地在对待的钢矩阵和定期驱散的RA代表了是三角形的形态学的发情被散布。XRD分析显示在矩阵的RA内容是不少于10%，并且TEM在矩阵内证明了那RA在优先的奥氏体边界被形成并且代表了是单个或成双的晶体。可锻的破裂从RA和铁酸盐从马氏体岛的边界发源。沿着谷物边界和一些宣传的裂缝通过了大铁酸盐谷物并且导致了transgranular骨折。

简介：Agroupofprojectionweldingexperimentsandjointstension-sheartestsarecarriedoutforcold-rolledsteelsheets,galvanizedsteelsheets(GSS)withouttreatment,GSSwithphosphatingandGSSwithsurfacegreasing,respectively.Theexperimentalresultsareregressivelyanalyzedonthecomputers,thentheprojectionweldedjointtension-shearstrengthcurveandtheperfectweldingcurrentsrangeofeachmaterialareobtained.Theresultsshowthatsurfacetreatmentsofgalvanizedsteelshaveeffectsontheirspotweldabilities.Amongthefourkindsofmaterials,GSSwithsurfacegreasinghavetheworstspotweldability,fortheyneedhigherweldingcurrentandhaveanarrowweldingcurrentrange.

简介：

简介：Recentinvestigationsindicatedthatmetalscanbeeffectivelystrengthenedbynumeroustwinboundaries(TBs)withtwin/matrixlamellarthicknessesinthenanometerregime.Superiorstrength-ductilitysynergieshavebeenachievedwiththenano-twinstrengtheningmechanism.Inthistalk,thenovelnano-twinstrengtheningwillbeappliedtoaustenitesteelsincluding316LstainlesssteelandaFe-Mnsteelinordertooptimizetheirstrength-ductilitycombinations.Thesteelsareprocessedbymeansofdynamicplasticdeformation(DPD,i.e.,plasticdeformationathighstrainrates).Single-phased(austenite)bulknanostructuredsteelspecimenswereprepared,consistingofnano-sizedgrainsembeddedwithnano-scaletwinbundles.Theas-preparednanostructuredsampleswereannealedatvariousconditions,resultinginpartialrecrystallizationofthenanostructuresandformingamixturestructureofcoarse-grainsembeddedwithnano-twinbundles.Strengthandductilityoftheaustenitesteelswithdifferentamountofnano-twinbundlesareanalyzed.Measurementsshowedthenano-twinstrengthenaustenitesteelscanbesuperstrong(withyieldstrengthabove1GPa)togetherwithaconsiderableductility(elongation-to-failure>20%).

简介：

简介：BasemetalsofdomesticpipelinesteelswereusedtostudytheeffectofMnoncorrosionpropertiesofSSCC(SulfideStressCorrosionCracking),andweldswerecarriedouttostudytheeffectofMnSoncorrosionpropertiesofHIC(HydrogenInducedCracking)bothinsolutionswithwethydrogensulfide(H2S).TheywererespectivelyconductedbyreferringtothestandardsofSSCCandHIC.TestingresultsrevealedthatwiththeincreaseofcontentMn,theresistanceofSSCCwillbedecreased,fromthepointofmetallurgicview,anditisMnelementnotCelementtoleadtothetestingresultsofSSCC.Meanwhile,evenundertheconditionwithoutinclusionsMnS,HICinweldsstilloccurred.Thatistosay,MnSisnotnecessaryforHIC,thepresenceoflocalbandedstructuresinwhichMnandPareinclinedtoaggregatecausetothephenomenaofHIC.

简介：Thispaperdescribesthealloydesignphilosophyfortheimprovementoflong-termcreepstrengthoftemperedmartensitic9Crsteel,includingweldedjoints.Thecreeplifetrisinverselyproportionaltotheminimumcreeprateεmintimestheincreaseincreepratebystraindlnε/dεintheaccelerationregionastr=1.5/[(εmin)（dlnε/dε）].Theparametersεminanddlnε/dεarecloselycorrelatedwiththetimetominimumcreepratetmandthestraintominimumcreeprateεm,whichcharacterizethecreepdeformationbehaviorinthetransientregion.Theboundaryandsub-boundaryhardeningisshowntobethemostimportantstrengtheningmechanismincreepof9Crsteelandisenhancedbyfinedispersionsofprecipitatesalongboundaries.TheadditionofboronreducesthecoarseningrateofM23C6carbidesalongboundariesnearprioraustenitegrainboundariesduringcreep.Theenhancementofboundaryandsub-boundaryhardeningincreasesthetmanddecreasestheεmin,whichimprovesthecreeplife.Theboundaryandsub-boundaryhardeningissignificantlyreducedinfine-grainedregionofheataffected-zone（HAZ）ofconventionalsteelP92weldedjoints,promotingTypeⅣfracture.InNIMS9Crboronsteelweldedjoints,thedistributionofcarbonitridesalongboundariesaresubstantiallythesamebetweentheHAZandbasemetal,suppressingtheTypeⅣfracture.

简介：Low-carbonbecomesahigh-frequencyandfashionablewordwhichgetsthegreatestconcernintheworld.Low-carbonreferstoaminimaloutputofgreenhousegasemissionsintothebiosphere,specificallyreferstothegreenhousegascarbondioxide.Toreduceenergyconsumptionofautomobile,moreandmorehighstrengthsteelsareusedbyvehiclecompanies.Tomeettherequestofvehiclecompanies,varioushighstrengthsteelsaredevelopedinsteelcompaniesallovertheworld.Ansteelcanprovide,ultra-lowcarbonbakehardening(BH)steels,dualphase(DP)steelsandtransformation-inducedplasticity(TRIP)steelswiththegradesofunder780MPa,uptonow.AHSSsteelshavemuchdifferentcomposition,microstructureandstrenghtthanconventionalvehiclesteels,sotherearesometroubleinproducingincoldrollingmills,forexample,difficulttojoin,poorthicknessandflatness,accuratetemperatureandvelocitycontrolandsoon.Toreducetheopportunityofstripbreakage,wehavedonemanyweldingexperimentsandspecialresearch.Now,DPandTRIPsteelscanbecontinuouslyproducedinAnsteel.Toassurethicknessandflatnessofstrips,weoptimizedthehotrollingparametertogetlowdeformationresistance,optimizedrollingoiltogetfitfrictionalcoefficientandfixonthetargatrollingcurve.Togetmoreaccurateandrepetitiveresultsovertheproductionshifts,theMathematicalModel(MM)isusedinAnsteel.TheMManalysesinformationtransmittedbyvarioussensorsandtransmitters,comparesthecollecteddatawiththechosenparametersandadjuststhesettingsofthevariouspiecesofequipmenttohoneontheparametersetpoints.Atpresent,thekeyproductiontechnologiesofAHSSweregraspedbycoldrollingmillAnsteel,andAnsteelisthefirstcompanytoapplytheTRIPwiththegradeof780MPa.

简介：Amodelwasdevelopedtosimulatethetemperaturedistributionandnuggetformationduringresistancespotwelding(RSW)ofzinc-coatedsteels.Itemploysacoupledthermal-electrical-mechanicalanalysissimulatingthedynamicRSWprocess.Temperature-dependentthermal-electrical-mechanicalmaterialpropertieswereconsideredincludingcontact-resistance.Thecontactareawasdeterminedfromacoupledthermal-mechanicalanalysis.Alayeroftransitionelementswasusedtorepresentthechangeofcontactareabykillingoractivatingelements.Theheatgenerationandtemperaturefieldwerecomputedinacoupledthermal-electricalmodel.Alltheseanalysesweresolvedusingthecommercialfiniteelementmethod(FEM)basedonANSYScode,andsomeadvancedfunctionswereusedbywritingaparagraphofcodesbytheauthors.Comparedwiththeresultsfromonlycoupledthermal-electricalmodelinwhichcontactareawasuniformduringthewholeprocess,theresultmatchesbettertotheexperimentalresults.

简介：Inthispaper,theeffectofplasticconstraintontheinitiationofductiletearsinfourdifferentshipbuildingstructuralsteelshasbeenexperimentallystudiedbymeasuringtheJ-integralandcrackopeningdisplacementCODatinitiationinthree-pointbendspecimenswithdeepandshallownotches.ExperimentalresultsofsevengroupsofdifferentstrengthalloysteelsshowthatbothδìandJìvaluesofductiletearfromtheshallowcrackspecimenswhichhavelessconstraintflowfieldaresignificantlyhigherthanthoseofdeeplynotchedspecimens.Slip-line-fieldanalysisshowsthat,forshallowcrack,thehydrostaticstressislowerthanthatfromstandarddeeplycrackedbendspecimen,whichdevelopsahighlevelofcracktipconstraint,providesalowerboundestimateoftoughness,andwillensureanundulyconservativeapproachwhenappliedtostructuraldefects,especiallyifinitiationvaluesofCODandJ-integralareused.

简介：Inrecentyears,nitrogen-alloyedstainlesssteelshavebeenaresearchhotspotinthefieldofstainlesssteelproductandtechnology.Nitrogen-alloyedausteniticstainlesssteelsdevelopedbyBaosteelandtheirapplicationsareintroduced.Thesesteelsarenitrogen-controlledproducts304Nand316LN,nitrogencontainingeconomicalproductsBNseriesandhigh-nitrogenstainlesssteel(HNS)series.Theresultsshowthatthepresenceofnitrogencansignificantlyimprovethestrengthandcorrosionresistanceofsteelproduced.Bynitrogenalloying,economicalausteniticstainlesssteelswithconsiderablylessnickelthan304canbeobtained;thecorrosionresistancesofthesesteelsarealmostthesameas304.Furthermore,byascientificapproachofnitrogenalloying,high-nitrogensteelof0.8%nitrogencontentisfabricatedunderthenon-pressurizedconditions,andthepittingpotentialofthissteelis>1.0V.Atpresent,nitrogen-alloyedsteelsdevelopedbyBaosteelarewidelyutilizedinthemanufactureofcryogenicstoragecontainers,transportationcontainers,andmanyhouseholdwares.

简介：Abstract:Inrecentyears,withattentionpaidtoglobalenvironmentalproblems,therehavebeenrequirementsforcontinuousimprovementofautomobilefueleconomyandexhaustgaspurificationrate.Thepropertiesoftheferriticstainlesssteels(FSS)usedtomakeautomobilepartshavebeenimproved.Thispaperintroducestheconstructionofautomotiveexhaustsystemsanddescribestheirmainfailurebehaviorsandcorrosionevaluationprocedures.